The ess in actress is not a diminutive and does not stand for less . The custom of designating the gender of persons performing an activity derives from languages in which every noun, whether referring to people, creatures, or objects, is "inflected," that is (assigned a gender), either male, female, or neuter.
In our language the practice of inflecting nouns has all but died, with a few notable exceptions. It is--or was until recently, at least--common practice to refer to ships and nations as female.
More notably, another exception is in the case of some words that refer to a person or persons, who, like it or not, do have sexes--or rather, genders, as we are told we should say nowadays. And thus, such words as actress and aviatrix.
The "hidden agenda of making women feel like fools for thinking they could compete with men" is not with those who continue to refer to female actors as actresses, but with the advocates of "non-sexist" language.